Combustion engines do not generate a constant torque, and exhibit irregularities caused by the successive combustion events in their cylinders. These irregularities generate vibrations that are capable of being transmitted into the gearbox, thereby causing therein particularly undesirable impacts, noise, and acoustic annoyances.
Motor vehicle transmissions thus have vibration filtering devices located upstream from the gearbox, in order to reduce the undesirable effects of vibrations and to improve the driving comfort of the motor vehicles.
Filtering devices of the inertial deflector type, which allow vibrations to be filtered selectively for a specific frequency range, are known. The inertial deflectors are generally tuned to filter vibrations for a given frequency corresponding to a resonant frequency of the transmission system.
As an example, the document US 2013 206529 discloses a transmission system equipped with an inertial deflector. The latter has an inertia mass that is fastened onto two guide washers, a web that is on the one hand arranged axially between the two guide washers and on the other hand is rotationally integral with a hub having splines intended to interact with an input shaft of a gearbox, and helical springs acting against the relative rotation of the guide washers with respect to the web. The guide washers and the web each have circumferentially oriented windows that are each intended to receive a helical spring. The circumferential ends of the windows have radial zones that constitute abutment seats intended for abutment of the ends of the helical springs. The windows configured in the guide washers have curved inner and outer edges allowing radial and axial retention of the elastic members. An inertial deflector of this kind has numerous elements, so that it is complex and expensive to manufacture.